Architectural Sustainability on the Impacts of Different Air- Conditioning Operational Profiles and Temperature Setpoints on Energy Consumption: Comparison between Mosques with and Without HVLS Fan in the City Center Mosques

Nur Amalina Syairah Mohamed1 , Zalina Shari1*, Nur Dalilah Dahlan1, Ibiyeye Aminat Idowu2

1Department of Architecture, Faculty of Design and Architecture, Universiti Putra Malaysia, Serdang Malaysia 2Department of Architecture, Faculty of Environmental Sciences, Kaduna State University, Kaduna, Nigeria

*[email protected]

The use of air-conditioning (AC) in conjunction with high-volume, low-speed (HVLS) fans has become a trend in retrofitted mosque buildings in Malaysia to improve thermal comfort conditions. However, the energy impact of operating AC and HVLS fan simultaneously is unknown. This study compares the annual energy consumptions between mosques with and without HVLS fan installed and investigates the optimum temperature setpoints and operational profile to improve the mosques' energy efficiency. The Building Energy Intensity (BEI) comparison did not clearly show the superiority between the two groups in terms of energy performance. The study found that both studied mosques could produce around 1-4.9% energy reduction when the AC temperature setpoint was increased by 1˚C and could result in the highest cost-saving of about 4.9% when the temperature was set at 27˚C. A 30-minute AC operation during each daily prayer, except Subuh, could save between 14.8-16.7% annual energy consumption and about 15.2-16.6% annual energy cost. The paper concludes that the selection of 24-27˚C temperature setpoints with a 30-minute AC operational profile during prayers time, considering Friday prayers and Ramadhan activities, produced 18.4-20.6% savings in energy cost. This study calls for reevaluations of AC temperature setpoints configuration standards and operational characteristics in mosque buildings to reduce energy consumption. This paper contributes to the development of future energy standards for mosque designs and operations in Malaysia.

Keywords: Temperature Setpoints, Operational Profile, Building Energy Intensity (BEI), High- Volume Low-Speed (HVLS) Fan, Air-Conditioning, Mosques, Malaysia

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1. INTRODUCTION energy efficient (Shah et al., 2015). However, the extent to which the concurrent operation of both AC and HVLS fans affects the mosques' energy Mosques are a religious building type that is an performance still remains unclear. Do these essential part of any Muslim civil society. They mosques achieve the required thermal comfort are unique buildings in terms of their function and while consuming the least energy? This paper operation. Mosques are used not only for praying argues that when the operations of both AC and religious purposes but also for community system and HVLS fans are improperly designed, functions. Operationally, they are occupied it could result in additional, unnecessary amounts intermittently for performing prayers five times a of energy. day, all year round. Each occupancy is either partial or full and lasts at the most for an hour. An AC system's ultimate goal is to provide better Worshippers do not usually arrive or leave the indoor thermal comfort for building occupants; mosque simultaneously during this hour but hence, the system's proper operations must avoid rather at random. However, a maximum energy wastage. The comfort level is higher when occupancy generally occurs during each prayer's an air-conditioned room is integrated with a actual performance, which lasts between 15 to 20 ceiling fan (Chen et al., 2020). The air movement minutes. Some exceptions to this pattern of created by the ceiling fan keeps the building's occupancy occur during weekly Friday prayers, occupants feeling comfortable, although the the Taraweeh prayers during the nights of the setpoint temperature of the AC is high. A study month of Ramadhan (fasting month), and during by Wang and Lin (2013) found that 40% of other special occasions such as lecturing and energy saving can be achieved in an intelligent seminar activities, where people tend to stay building using a smart control AC and ceiling fan. longer in the mosques (Al-Homoud et al., 2005a). They explained that the airflow from a ceiling fan Understanding the functions and operations of could provide a cooling sensation to the mosques reflect the importance of thermal occupants. The strategy of increasing the AC design for occupants' comfortable praying thermostat temperature and adjusting the ceiling experience. Intermittent occupancy means fan speed to the medium can help achieve a mosques may not perform thermally the same as comfortable and energy-efficient environment typical commercial buildings. Installations of air- (Hawaii Natural Energy Institute, 2017). conditioning (AC) systems in mosque buildings to achieve the required thermal comfort have become common in the hot and humid climate region, particularly in Malaysian urban areas (Department of Standards Malaysia, 2014; Hussin et al., 2014). AC systems are responsible for the significant percentage of energy consumption in buildings. Malaysia's building sector contributes 40.5% of total national energy consumption (Malaysia Energy Commission, 2019) and 43.4% of total carbon dioxide emissions (Mohd Safaai et al., 2011). Figure 1: High-volume low-speed (HVLS) fan Recently, the use of AC system in conjunction Source: Author with high-volume, low-speed (HVLS) fans to achieve the desired thermal comfort in the main Currently, little information on energy prayer halls has become a common trend in performance or building energy intensity (BEI) of mosques located in Malaysian urban areas, such mosque buildings is available. An early study by as in Kuala Lumpur, Selangor and Johor (Othman Al-Homoud et al. (2005a) showed that the et al., 2019; Yendo et al., 2015). As shown in average BEI value of five mosques in Saudi Arabia was 167 kWh/yr/m2. The figure increased Figure 1, the HVLS fan is a new generation of 2 ceiling fan with a large fan diameter design that to 181.9 kWh/yr/m after the subsequent data can cover a large area at a slow-motion speed collections and analyses (Al-Homoud et al., (Moshfeghi et al., 2014). Specifically, it has 2005b). In Malaysia, a recent study by Hussin et airfoil blades measuring a minimum of 2.1-meter al. (2019) on five retrofitted air-conditioned in diameter with a rotation in the range of 50-125 mosques in Penang revealed that three of the mosques demonstrated BEI values of between 70 revolutions per minute to produce a minimum 2 airflow of 140,000 cubic feet per minute to 124 kWh/yr/m , which are lower than the BEI of office buildings by Saidur and Masjuki (130 (Moshfeghi et al., 2014). HVLS fan does not only 2 provide comfort, but the fan's motor is also kWh/yr/m ). The fourth mosque's BEI was 135 kWh/yr/m2, while the fifth was 323 kWh/yr/m2, a

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significantly higher value than the BEI of al., 2020; Xu et al., 2013). hospitals (244.8 kWh/yr/m2) by Moghimi et al. (2011). As Hussin et al. (2019) is so far the only Among the behavioural interventions to reduce study on mosque BEI in Malaysia, it was energy consumption are fine-tuning the AC considered appropriate for their BEI values to be temperature setpoints and revisiting the AC used as the baseline in this paper. The high BEI operational profiles. An adjustment to the AC results from Al-Homoud et al. (2005b) and temperature setpoints is made according to the Hussin et al. (2019) highlight the need for more desired indoor thermal comfort (Aghniaey & energy retrofit measures in mosque buildings. Lawrence, 2018; Yan et al., 2019b), but research Although these studies focused on air- has shown that an increase of 1oC in AC conditioned mosques, they ignored the usage of temperature setpoint will reduce at least 7% of HVLS fans. energy consumption (Ho et al., 2009). A growing number of studies conducted in hot climatic Energy retrofit is one of the instruments used to regions show that adjustments to the AC improve buildings' energy performance (Rogeau temperature setpoints significantly impact et al., 2020). There are two types of energy building energy consumption. These studies were retrofits: technical configurations and conducted in Singapore (Tom, 2008; Tushar et behavioural interventions (i.e. human-based al., 2016), Malaysia (Mustapa et al., 2017), retrofits). Technical configurations involve Thailand (Yamtraipat et al., 2005), Indonesia rearranging, replacing, adding and deleting some (Hamzah et al., 2018; Sunardi et al., 2020) and existing components of the buildings (Brown et South Africa (Wang et al., 2013). These studies al., 2014; Mancini & Nastasi, 2019; Sánka & have recommended different ranges of Petráš, 2019). The discussion of this approach temperature setpoints for thermal comfort. revolved around better bioclimatic designs and Although there is no specific point when the more energy-efficient insulation, windows and effect of temperature is dissatisfactory in terms of HVAC systems (Ariosto et al., 2019; Fang & thermal comfort to the users, controlling the AC Cho, 2019; Jankovic, 2019). Technical temperature setpoints has been reported to be one configurations type of energy retrofits has been of the means of managing the building energy widely studied for schools (Ali & Hashlamun, consumption (Aghniaey & Lawrence, 2018). 2019; Tahsildoost & Zomorodian, 2015), commercial (Li et al., 2020), offices (Mohamad et A reevaluation of the AC operational profile, on al., 2018; Somasundaram et al., 2020) and the other hand, involves strategising the AC residential buildings (Friedman et al., 2014; Wu operation schedule based on a deep understanding et al., 2017). Despite their advantages, such of the building usage, occupancy load, climate retrofit measures are complex as they involve factors, and occupancy duration of the building large-scale modifications, high upfront capital (Knight, 2016; Xia et al., 2019; Yang & Becerik- cost, and long implementation time (Cajot et al., gerber, 2014). For example, the AC operational 2017; Mirakyan & De Guio, 2013) profile for a mosque may differ from other building types as mosques generally have Behavioural intervention or human-based intermittent occupancy. Previous literature has retrofits, on the other hand, refers to also suggested that AC operating profiles are modifications of human (occupants or building expected to significantly impact the mosques' managers) behaviour or actions that they can take thermal and energy performance (Al-Homoud et to improve the existing building operation al., 2005b; Al-Shaaban & Alohaly, 2017; towards achieving energy efficiency (Ascione et Budaiwi & Abdou, 2013; Omar et al., 2020). al., 2020; Barthelmes et al., 2017; Pan et al., Furthermore, the effectiveness of the operational 2017). Examples of such actions include profile depends on the understanding of the AC adjusting the HVAC thermostat setpoints, response time and the amount of time needed for opening windows for natural ventilation, the AC system to cool down space to the reducing the use of artificial lightings, equipment temperature setpoint (Hui et al., 2017). The and appliances, to name a few (Dall'O' et al., function and operational strategies of a mosque 2012). Many studies have been conducted on depend on the end-users, of whom the designers behavioural intervention types of retrofits have no or less control (Atmaca & Gedik, 2019; (Dall'O' et al., 2012). Human-based retrofits are Hussin et al., 2019). Therefore, it is crucial to generally more cost-effective (i.e. they come with involve the end-users in implementing energy little or no implementation costs) and practical conservation measures without compromising the than technical retrofits (Xia et al., 2019). indoor environmental conditions of building However, the success depends on the occupants- users. It could be argued that behavioural building interaction and the occupants' and interventions or human-based retrofits are more management staff's level of commitment (Jami et suitable for buildings with intermittent occupancy

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such as mosques than technical retrofits. Sepang and Petaling Jaya. Malaysia's climate is categorised as hot and humid throughout the The evidence gathered here suggests that year, with the mean radiant temperature of 28o behavioural interventions through AC and the average highest daytime temperature of temperature setpoints and operational profile 38oC. The relative humidity ranges between 65% optimisations can achieve cooling energy to 90%, with the annual rainfall between reduction and thermal comfort improvement. It is 1800mm and 3900mm. Generally, Malaysia's also necessary to determine a suitable range of climate characteristics are uniform temperature, AC temperature setpoints and integrate the high humidity, light wind, and copious rainfall cooling duration into AC operating profiles of (Malaysia Meteorological Department, 2019). mosques in Malaysia. Moreover, there is a need All countries in the Southeast Asia region have for a clear understanding of the energy impacts of the same tropical climate type (Mcknight & operating AC and HVLS fans in mosques and Hess, 2000). how behavioural interventions could be undertaken to minimise the energy consumption As of 2019, there were 6,446 mosques in without compromising their indoor thermal Malaysia, 396 of which were located in Selangor, comfort levels. To the best of our knowledge, and 71 in Kuala Lumpur. The number of there is no academic paper in the building mosques is expected to increase due to the literature that focuses on this aspect. This paper growth of the Muslim population in Malaysia aims to fill this gap. The objectives of this paper (Department of Statistic Malaysia, 2019). About are 1) to analyse and compare the BEI between 70% of the mosques in Malaysia can air-conditioned mosques with and without HVLS accommodate between 1000 to 3500 fan, and 2) to assess the energy-saving potential worshippers at a time (Department of Islamic of air-conditioned mosques through different AC Development Malaysia, 2020). Therefore, the temperature setpoints and operational profiles mosques of this size were selected for this study. adjustments. The findings motivate the need to Although a mosque can generally accommodate revisit AC setpoint configuration and operational 3000 people, the calculation of area per profile standards in mosque buildings, either as a worshipper revealed that the main praying hall segment of individual building retrofit could only hold about 550 worshippers preparation or as a segment of energy standards (Malaysia Economic Planning Unit, 2015). for mosque designs and operations in Malaysia. Architecturally, mosques are generally rectangular in plan with walled enclosures, This paper is structured as follows. The second windows and a prominent roof above the main part of the paper reviews the recent studies on the prayer hall. The building height varies from one proper use and control of AC systems for energy to three stories, with a void above the prayer hall. efficiency and HVLS fans' applications for thermal comfort. The third part discusses the 2.2 Case Studies: Selection Parameters, study's methodological details, which comprise Instrumentation and Limits the techniques in selecting the mosques, collecting the electricity bills, and conducting The selection of specific mosques for the study energy simulations. The comparison of BEI was based on the following parameters: 1) located results between mosques with and without HVLS in areas with the same weather profile and prayer fans through behavioural interventions is times, 2) no older than 20 years old, 3) built with presented in the fourth section, whilst the fifth similar building materials, 4) have similar section discusses their implications and existing operational profiles and use split-unit AC system limitations. Finally, the paper concludes with a type in the main prayer halls, and 5) able to summary of the essential findings and provide two years of electricity bill data (January recommendations for future work. 2017 to December 2018). The study identified 54 mosques that met the research parameters 1 and 2. In order to confirm parameters 3 and 4, site 2. METHODOLOGY visits were conducted to all 54 mosques. During the visits, the survey form by Ibrahim (2015) was 2.1 Site Description and Mosque Selection used to record data of the mosques. The survey form contained three sections. The first section The mosques selected for the study are located in recorded the general building information such as o the Klang Valley (lying between 2.6817 N and roof type, year of construction, total area and total o 101.6813 E), an urban conglomeration in praying hall area, dimensions of the mosque, Malaysia centred in Kuala Lumpur. Klang window types, and any internal shading used. The Valley includes adjoining cities and towns in second section recorded the building operation Selangor, namely, Klang, Hulu Langat, Gombak, schedules, including the zoning of the mosque,

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air-conditioned area and the type of verandah. materials, and opening types were also recorded. The final section required inputs on the descriptions of the building energy usage such as This study adopted the formula by Saidur and the type of lighting system, type of AC system, Masjuki (2008) to calculate the Energy Intensity types of fans, power distribution panel, and Index (ACEII) in kW/m2/yr, as shown below: socket points. Floor plans were sketched in the form if drawings were not available. = 𝑛𝑛 (1) ∑𝑖𝑖 𝐴𝐴𝐴𝐴𝐴𝐴 The study finally confirmed that the 54 identified 𝐶𝐶𝐶𝐶𝐶𝐶 where 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴AEC is the total value of energy mosques met the research parameters 1-4, and consumption of equipment i to n and CFA is the they were classified into two groups, i.e., cooling floor area (m2). The air conditioning cost mosques with HVLS fan (Group A: 14 nos.) and index (ACCI) in RM/year/m2 was estimated using those without HVLS fans (Group B: 40 nos.). the following equation: However, due to time and cost constraints and

some restrictions in obtaining permission from = the mosques' management, only three mosques 𝑛𝑛 (2) from each group were selected. Their general ∑𝑖𝑖 𝐴𝐴𝐴𝐴𝐴𝐴 𝐶𝐶𝐶𝐶𝐶𝐶 descriptions are shown in Table 1. These six where the𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 ratio is the sum of energy consumed in mosques were considered representative. They Malaysia Ringgit (RM) to the cooling floor area met all the selection parameters, including (m2) (Saidur & Masjuki, 2008). parameter 5. Floor plans were obtained except for two mosques (A3 and B3), of which detailed Three mosques using HVLS fan (Group A) and measurements had to be conducted due to the three mosques without HVLS fan (Group B) were nonexistence of architectural drawings. More site selected as case studies. Although the sample size visits were conducted to all these six mosques. is small, the results would help the mosques' Specifically, detailed walk-throughs were management to make wise decisions on energy performed to understand the mosques' layout and conservation measures. The BEI values of identify the cooling areas and parts of the mosques in both groups were calculated by using buildings that differed from the original building two-year electricity bill data (January 2017 to plans. Interviews with the mosques' December 2018) and formula equations (1)(2) administration staff were carried out to have above. insights into the mechanical ventilation operations. 2.4 Data Analysis

2.3 Comparison of energy consumption and The values of the normalised total energy cost consumption and cost of all mosques were analysed by using SPSS statistical software. All The Building Energy Intensity (BEI) was data on energy used (kWh) and cost (RM), which calculated to compare the energy consumption were generalised for two years, were keyed in. levels among the selected mosques and between Data of each mosque were sorted according to the mosques and the Malaysian Standard months and years. Later two separate independent (MS1525: 2019)(Department of Standards sample t-tests were performed to compare Malaysia, 2019) as well as results from previous mosques in both groups regarding energy studies on mosques. In light of the lack of green consumption and cost within a two-year mosques in Malaysia, the study used the Malaysia timeframe. Each mosque in group A was Standard (MS1525: 2019) and previous studies as compared to the other three mosques in group B, the basis of comparison. MS1525 stated that the resulting in 9 t-tests for each group, hence, 18 t- BEI for office buildings should be less than 200 tests in total. The independent t-test results 2 kWh/year/m , while Moghimi et al. (2011) determined whether the two groups of mosques revealed the BEI for hospital buildings is 245 are statistically different in terms of their level of kWh/year/m2. Since mosques do not have a energy consumption. This was made by similar cooling floor area, energy consumption producing a statistical mean (i.e. the average used and energy cost need to be generalised. The usage to derive the central tendency of the data for two of AC relatively affects the thermal comfort of the years). The annual mean values of electricity occupants. Therefore, the variables that affect the consumption and cost of all mosques were mosques' cooling load and indoor thermal generated, compared and ranked using the SPSS comfort were considered in this study. Any software. From the ranking, the mosque with the sensible heat gain and latent heat gain, lightings, highest "mean energy consumption" and "mean fans, computers and plug points were considered. energy cost" was selected to represent each group. The U-value of the mosques' walls, roof The hypothesis for the t-test is explained in the

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result section. studies was used to validate the model, hence establishing reasonable confidence in the 2.5 Energy Simulation simulation results. The operational profile used for the simulation reflected the existing The mosque with the highest BEI from each occupancy patterns of the mosques, i.e. five times group was simulated using IESVE Software to daily prayers, Friday prayers, and Ramadhan determine the best temperature setpoints and month timings. The operational profile also took operational profile that resulted in the most into account the lightings, fans and air significant reduction in energy consumption. The conditioners used in the buildings. Both mosques simulation's input data include the building's used split units AC with different capacities. The geographical location, the three-dimensional size of the air-conditioners used was assumed to geometry form and orientation, the building be adequate for the total area covered. The materials' thermal abilities, the type and temperature setpoint was recorded at 19˚C. efficiencies of the cooling and lighting elements, External climatic data used in the simulation were and the internal gains from electrical appliances real data obtained from the Malaysian and building occupants. These data were Meteorological Department. A simulation period obtained from the architectural drawings and of one year was selected with a simulation time official construction plans. The occupants' energy step of 10 minutes, a reporting interval of 60 usage data were gathered from the interviews that minutes, and a preconditioning period of 10 days, asked about their daily prayers routines. as recommended in the IESVE guidelines.

The data were subsequently drawn in Model IT 3. RESULTS before the main module software ApacheSim was

used to perform the numerous dynamic thermal 3.1 Energy consumption and cost impact using simulations. The software also allowed the Building Energy Intensity (BEI) customisation of lighting, equipment, and

occupancy profiles based on the internal heat gain Figure 2 shows the BEI value of each mosque. value. This study utilised the default settings of Although the highest BEI is a mosque from group "one occupant per 1.4m2 floor area" for the A, the second highest is from group B. The two occupancy and 70W/person for the sensible heat mosques that had exhibited the highest BEI gain. In the ApacheSim module, the building's values were A1 (Wangsa Melawati Mosque) and specific construction elements were built based B2 (UTM Mosque), with the values of 230 on the specification data gathered during the kW/m2/yr 191 kW/m2/yr, respectively. The walk-through audit. Building areas were grouped lowest BEI among the six case studies was according to their thermal zones, i.e. air- produced by mosque A3 (Alam Damai Mosque. conditioned or non-air-conditioned areas. A one- year period of electricity bill data of both case

400 323 300 230 191 200 151 152 200 111 133 135 100 0 BEI (kWh/m2/yr) A1 A2 A3 B1 B2 B3 C1 C2 C3 WITH FAN WITHOUT FAN BASELINE IN MALAYSIA Mosque

(With Fan) A1: Wangsa Melawati, A2 : Bandar Baru Ampang, A3: Alam Damai (Without Fan ) B1 : Kota Damnsara, B2 : UTM, B3: Hidayah (Benchmark): C1: MS1525(2019), C2&C3 : Hussin et.al,(2019)

Figure 2: Building Energy Intensity (BEI) of the six studied mosques

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Table 1: Selected six mosques as case studies

GROUP A: WITH HVLS FAN GROUP B: WITHOUT HVLS FAN Code and name A1: Wangsa A2: Bandar Baru A3: Alam Damai B1: Kota Damansara B2: UTM Mosque B3: Hidayah Mosque Melawati Mosque Ampang Mosque Mosque Mosque Image (Source : Author)

Location Wangsa Melawati, Ampang, Selangor Cheras, Selangor Petaling, Selangor Kuala Lumpur Sg. Penchala Kuala Lumpur Kuala Lumpur Total floor area 930 1669 2120 2226 2818 2672 (m2) Total cooling 550 712 700 1122 919 784 Area (m2) No. of storey 1 1/2 1 2 1 1/2 1 1/2 2 Roof material Metal dome on Flat Metal dome roof on Metal dome on Flat Metal dome roof on Metal dome on Flat Metal dome on Flat roof with 6mm metal pitch roof with roof with 6mm metal pitch roof with roof with 6mm roof with 6mm perimeter floating 6mm perimeter floating perimeter floating 6mm perimeter floating perimeter floating perimeter floating glass glass glass glass glass glass Type of Brick wall and plaster construction Window type Three-sided perimeter casement/louvres and three-sided sliding door Verandah Three-sided verandah Fan Ceiling, wall and stand fans AC type Wall type, approximately 32horse power Lighting System Dominated by fluorescent lighting

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Table 2 compares the BEI values from this study Homoud, et al., i.e. 167 kW/m2/year (Al-Homoud with the previous studies by a few scholars. It is et al., 2005a) and 181.9 kW/m2/yr (Al-Homoud et interesting to note that the BEI values of these two al., 2005b), and by Hussin et al. (2019), i.e. 135 mosques are higher than those reported by Al- kW/m2/yr.

Table 2 : Results of Building Energy Intensity (BEI) and cost

Description RM/ yr kWh/yr CFA ACCI Average BEI (kW/m2/yr)

Mosques from this Study (Group A: With HVLS fan) A1: Wangsa Melawati Mosque 70,399 133,502 550 128 230 A2: Bandar Baru Ampang Mosque 64,936 10,467 712 91.2 151 A3: Alam Damai Mosque 38,884 76,741 700 55.6 111 Mosques from this Study (Group B: Without HVLS fan) B1: Kota Damansara Mosque 70,454 148,945 1122 62.8 133 B2: UTM Mosque 93,601 177,693 919 101.9 191 B3: Hidayah Mosque 66,680 122,026 784 85.1 152 Mosques from Other Studies Hussin et al. (2019): • Mosques 1-4 (split unit AC) <135 • Mosque 5 (centralised AC) 152.8 323 Al-Homoud et al. (2009) <202 Al-Homoud et al. (2005a) 167 Al-Homoud et al. (2005b) 181.9 MS1525: 2019 (Department of Standards Malaysia, 200 2019) Moghimi et.al (2011) 245 Note: CFA= Cooling Floor Area; ACCI = Air Conditioning Cost Index The exchange rate of Malaysia Ringgit to U.S. Dollars is 0.24 (as of 9 August 2021)

3.2 Comparison of Mosque in terms of Energy The t-test results of energy consumption in Table Consumption and Cost 3 show that seven pairs of compared mosques had p-value < 0.05; hence, the null hypothesis was The independent t-tests were conducted to rejected. This indicates that there were statistically determine whether the two groups of mosques significant differences in energy consumptions differed regarding the level of energy between the compared mosques. However, the consumption. The results of the energy comparison between A2 (Bandar Baru Ampang consumption comparisons, i.e. the p-values Mosque) and B1 (Kota Damansara Mosque), as produced by independent t-tests, associated with well as A2 (Bandar Baru Ampang Mosque) and the six mosques identified the most energy- B3 (Hidayah Mosque), resulted in p-value > 0.05; efficient air-conditioned mosque. The assumed hence the null hypothesis was accepted, indicating hypothesis of the t-tests is as follows: that the differences in energy consumptions were negligible. Regarding the t-test results of energy Null hypothesis (H0): The two compared costs, Table 3 indicates that there were statistically buildings ( 1= 2) are equal in energy significant differences between all compared consumption, therefore H0: 1= 2 mosques (p-values < 0.05), except between μ μ mosque A2 (Bandar Baru Ampang Mosque) and Alternative hypothesis (H1):μ Theμ two compared mosque B3 (Hidayah Mosque), where the buildings are unequal in energy consumption, difference was negligible (p-value > 0.05). therefore H1: 1 2. Based on the mean values presented in Table 3, a The t-test resultsμ ≠ ofμ the electricity cost comparison ranking of the mosques is shown in Table 4, where associated with the six mosques identified the number "1" indicates the best mosque and number most energy-efficient mosque. Similar to the "6" indicates the worst mosque in terms of mean energy consumption comparisons, the electricity energy consumption and cost. The ranking is a cost comparisons also involved nine separate t- subjective ranking of the annual mean of energy tests. consumption and cost. Table 4 shows that the ranking based on energy consumption is similar to

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the ranking based on energy cost. This similarity fans. However, the second-best mosque was a is unsurprising since energy consumption is mosque without the HVLS fan, i.e. B1 (Kota closely related to energy cost. Interestingly, both Damansara Mosque). This unclear pattern of the best and the worst mosques, namely, A3 (Alam rankings between mosques with and without Damai Mosque) and A1 (Wangsa Melawati HVLS fans may be due to different AC and fan Mosque), respectively, were mosques with HVLS operation profiles used.

Table 3 : T-tests results of energy consumption and cost

RESULTS FOR ENERGY RESULTS FOR ENERGY COST CONSUMPTION HYPOTHESIS Mean Probability Mean Probability (MOSQUES) (Standard (p-value) (Standard Deviation) (p-value) Deviation) A1 and B1 A1 B1 A1 B1 Wangsa Melawati Mosque and Kota 19.2 11.0 0.001 10.3 5.4 0.001 Damansara Mosque (±1.91) (±2.2) (±1.00) (±1.03) A1 and B2 A1 B2 A1 B2 Wangsa Melawati Mosque and UTM Mosque 19.2 17.3 0.001 10.3 8.6 0.001 (±1.91) (±2.12) (±1.00) (±1.01) A1 and B3 A1 B3 A1 B3 Wangsa Melawati Mosque and Hidayah 19.2 12.6 0.001 10.3 7.3 0.001 Mosque (±1.91) (±3.33) (±1.00) (±1.44) A2 and B1 A2 B1 A2 B1 Bandar Baru Ampang Mosque and Kota 12.6 11.0 0.06 6.9 5.4 0.001 Damansara Mosque (±3.31) (±2.22) (±1.55) (±1.02) A2 and B2 A2 B2 A2 B2 Bandar Baru Ampang Mosque and UTM 12.6 17.3 0.001 6.9 8.6 0.001 Mosque (±3.31) (±2.13) (±1.55) (±1.02) A2 and B3 A2 B3 A2 B3 Bandar Baru Ampang Mosque and Hidayah 12.6 12.6 1.00 6.9 7.3 0.35 Mosque (±3.31) (±3.33) (±1.55) (±1.45) A3 and B1 A3 B1 A3 B1 Alam Damai Mosque and Kota Damansara 9.3 11.0 0.001 4.9 5.4 0.04 Mosque (±0.96) (±2.22) (±0.54) (±1.03) A3 and B2 A3 B2 A3 B2 Alam Damai Mosque and UTM Mosque 9.3 17.3 0.001 4.9 8.5 0.001 (±0.96) (±2.13) (±0.54) (±1.01) A3 and B3 A3 B3 A3 B3 Alam Damai Mosque and Hidayah Mosque 9.3 12.6 0.001 4.9 7.3 0.001 (±0.96) (±3.33) (±0.54) (±1.44)

Table 4 : Ranking of mosques in terms of energy consumption and cost

HVLS Fan Mean Mean Ranking Building Name (Energy Consumption) (Energy Cost) 1 A3: Alam Damai Mosque Yes 9.3 4.9 2 B1: Kota Damansara Mosque No 11.0 5.4 3 A2: Bandar Baru Ampang Mosque Yes 12.6 6.9 4 B3: Hidayah Mosque No 12.6 7.3 5 B2: UTM Mosque No 17.3 8.6 6 A1: Wangsa Melawati Mosque Yes 19.2 10.3

Subsequently, the mosque with the highest energy consumption and cost from each group 3.3 Validation of Stimulation Models was brought into the simulation process to determine the best operational profiles and Before the simulations on temperature setpoints temperature setpoints to improve its energy and operational profiles were conducted, the efficiency. Therefore, A1 (Wangsa Melawati developed models were validated by comparing Mosque), ranked last in energy consumption and the simulated monthly annual energy cost, and B2 (UTM Mosque), ranked fifth, were consumption results with the mosques' actual chosen to represent a mosque with and without energy consumption, i.e. monthly annual HVLS fan, respectively. electricity bills for 2017. The results showed that

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the simulated energy profile was not more than The resulted energy consumption, BEI and 8.4% of the actual electricity bills; hence, the energy cost from each 1oC temperature increment models were validated, and there was good for both mosques are summarised in Table 5. confidence that the simulation results would be Only the temperature setpoints were increased for reliable and valid. this simulation, while the baseline AC operational profile remained the same. The results showed 3.4 Energy Simulation Result On Temperature that the total energy and cost savings for Wangsa Setpoints Melawati Mosque were 4.6% and RM3106.00, respectively. For UTM Mosque, the respective According to the actual usage, the temperature total energy and cost savings were 3.8% and setpoint for A1 (Wangsa Melawati Mosque) and RM3456.00. It appears that the adjustment to AC B2 (UTM Mosque) was set at 19˚C; hence, used temperature setpoints could result in higher as a baseline for this study. From this baseline energy and cost savings for A1 (Wangsa temperature, it was increased at 1oC to up to 27˚C. Melawati Mosque) than B2 (UTM Mosque) .

Table 5 : Simulation results based on different temperature setpoints for Wangsa Melawati Mosque and UTM Mosque

A1: Wangsa Melawati Mosque (with HVLS fan)

Temperature 19°C 20°C 21°C 22°C 23 °C 24°C 25°C 26°C 27°C setpoint (°C)

Total Energy 119,343 118,655 117,889 117,122 116,350 115,577 114,780 114,035 113,325 Consumption (kWh) Cooling area (m2) 550 550 550 550 550 550 550 550 550 BEI (kWh/yr/m2) 216 215 214 213 212 210 209 207 206

% BEI Saving - 0.5 0.9 1.4 1.9 2.8 3.2 4.2 4.6

Cost (RM) 60,901 60,513 60,213 59,732 59,338 58,944 58,547 58,157 57,795

Saving (RM) - 388 688 1169 1563 1957 2354 2744 3106

B2: UTM Mosque (without HVLS fan)

Total Energy 171,269 170,434 169,597 168,754 167,909 167,057 166,205 165,353 164,493 Consumption (kWh) Cooling area (m2) 919 919 919 919 919 919 919 919 919

BEI (kWh/yr/m2) 186 185 184 183 182 182 181 180 179

% BEI Saving - 0.5 1.1 1.6 2.2 2.2 2.7 3.2 3.8

Cost (RM) 87,347 86,921 86,494 86,064 85,633 85,198 84,764 84,330 83,891

Saving (RM) - 426 853 1283 1714 2149 2583 3017 3456

Note: The exchange rate of Malaysia Ringgit to U.S. Dollars is 0.24 (as of 9 August 2021)

3.5 Occupancy Profile 17:00 except for Saturday, Sunday and public holidays. Understanding a building's occupancy profile or pattern is important in scheduling the building's The baseline AC operation profiles are grouped AC operation. The uniqueness of mosque according to the three occupancy profiles as buildings is seen from their intermittent follows: occupancy profile, primarily based on prayer times. The operational profiles of the Wangsa 1. Daily profile: This was according to the five Melawati Mosque and UTM Mosque are similar, prayer times, namely Subuh (dawn, before as explained below. It is important to note that sunrise, 5:30 to 6:30), Zohor (midday, after the AC operational profile of both studied the sun passes its highest, 12:30 to 13:30), mosques also included the mosques' Asar (the late part of the afternoon, 16:00 to administration office because the space was air- 17:00), Maghrib and Isyak (between sunset conditioned and operated daily from 8:00 to and midnight, 19:00 to 21:00).

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25˚C by midnight. These data were based on 21 2. Friday profile: This was similar to the daily years of weather data from the Malaysian profile except during Zohor from12:30 to Meteorological Station in Subang, Klang 15:00, which is longer in duration to Valley, Selangor. This explanation indicates the accommodate Friday's sermon. trend of low and high air temperature within a day, which can be mapped to the prayer times. 3. Ramadhan profile: This had different daily For example, during Zohor prayer (after operation time during Zohor, Maghrib and midday), the air temperature is uncomfortably Isyak. Most worshippers would spend some high. However, the temperature during Subuh time during the Zohor hours in the month of (dawn) is within an acceptable thermal range. Ramadhan for itikaf (period of retreat in a The air temperature decreases during Asar mosque) or tadarus (recite Quran in a (afternoon) and further down until Isyak group). Therefore, the operations time of (nighttime). Therefore, with an appropriate AC Zohor during Ramadhan is 12:30 until operational profile strategy, thermal comfort can 14:00. The operation time for Maghrib and be achieved during prayer times. Isyak are continuous from sunset until almost midnight (19:00 to 23:00). This is With the understanding of the air temperature because worshippers begin to break their fast and acceptable thermal comfort, Table 6 (top at the mosque during Maghrib and continue half) shows the baseline and proposed with Isyak prayer, followed by Tarawikh operational profiles (1A-1F) for both selected prayer (additional prayer after Isyak prayer). mosques. The columns marked with (√) follows the time of the baseline profile (existing profile). It is of paramount importance to understand the In contrast, those marked with (X) indicates no outdoor air temperature and building thermal air-conditioning was operated during that comfort to determine the best AC operational particular period. Under the proposed operation profile, including the temperature setpoint. Tang profile, the new AC operation duration is stated et al. (2017) highlighted that the average dry in relevant columns using a 24-hour time bulb temperature of Kuala Lumpur at 7:00 am is format. The adjustments of AC operation times 26˚C and subsequently increase and peak at were made by considering the air temperature 31.5˚C at around 3:00 pm before going back profile and the time needed to cool down spaces. down to 28˚C at 6:00 pm and further down to

Table 6 : Simulation results based on different operational profiles at 190C temperature setpoint for Wangsa Melawati Mosque (A1) and UTM Mosque (B2)

Operation profile Baseline 1A 1B 1C 1D 1E 1F Setting Cooling 19oC 19oC 19oC 19oC 19oC 19oC 19oC point Subuh Daily/Friday/ √ X X X X X X Ramadhan 0530-0630 Zohor Daily √ √ √ √ 1300-1330 √ 1300-1330 1230-1330 Friday only √ √ √ √ √ √ 1230-1430 1230-1500 Ramadhan only √ √ √ √ √ √ 1300-1400 1230-1400 Asar Daily/Friday/ √ √ 1630-1700 1630-1700 1630-1700 1630-1700 1630-1700 Ramadhan 1600-1700 Maghrib &Isyak Daily /Friday √ √ √ X X 1900-2030 X 1900-2100 Maghrib X X X 1900-1930 1900-1930 X 1900-1930 Daily/Friday Isyak Daily/Friday X X X 2000-2030 2000-2030 X 2000-2030

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Ramadhan only √ √ √ √ 1900-2200 1900-2200 1900-2200 1900-2300 Total energy Wangsa Melawati 119,343 114,939 110,871 105,918 102,205 107,646 101,323 Mosque (A1) UTM Mosque 171,269 159,113 154,767 148,539 143,717 149,545 142,904 (B2) Total BEI (kWh/yr/m2) Wangsa Melawati 216 208 201 192 185 195 184 Mosque (A1) UTM Mosque 186 173 168 161 156 162 155 (B2) Cost Index (RM)

Wangsa Melawati 60,901 58,619 56,544 54,018 52,124 54,899 51,674 Mosque (A1) UTM Mosque 87,347 81,147 78,930 75,754 73,295 76,267 72,881 (B2) % Saving in BEI

Wangsa Melawati - 3.7 6.9 11.1 14.4 9.7 14.8 Mosque (A1) UTM Mosque 6.9 9.7 13.4 16.1 12.9 16.7 (B2) % Saving in Cost

Wangsa Melawati - 3.7 7.2 11.3 14.4 9.9 15.2 Mosque (A1) UTM Mosque - 7.1 9.6 13.3 16.1 12.7 16.6 (B2) Notes : (√ ) indicates that the air conditioner is operated during that prayer time using the existing profile. ( X) indicates that the air conditioner is not operated. The exchange rate of Malaysia Ringgit to U.S. Dollars is 0.24 (as of 9 August 2021) : Amended operation profile from existing.

that the operational profile 1F produced lower 3.6 Building Energy Simulation Result on BEI for UTM Mosque (155kWh/yr/m2) than Operational Profiles Wangsa Melawati Mosque (184 kWh/yr/m2). The BEI percentage reduction for UTM Mosque and Wangsa Melawati Mosque was 16.7% and Using the baseline temperature setpoint of 19˚C, 14.8%, respectively, while the cost-saving both mosques were simulated using six different percentage was 16.6% for UTM and 15.2% for operational profiles, labelled as "1A to 1F". The Wangsa Melawati Mosque. results presented in Table 7 (bottom half) show

Table 7 : Simulation results based on 1F operational profile with different temperature setpoints for Wangsa Melawati Mosque (A1) and UTM Mosque (B2)

Existing Alternative Different setpoint with 1F operational profile Operation profile Baseline 1F 2 3 4 5 Setting Cooling point 19oC 19oC 24oC 25oC 26oC 27oC A1: Wangsa Melawati Mosque Total energy (kW) 119,343 101,323 97,441 96,656 95,876 95,146

Total BEI 216 184 177 176 174 172 (kWh/yr/m2) Energy Saving (%) - 14.8 18.1 18.5 19.4 20.3 Cost (RM) 60,901 51,574 49,694 49,294 48,896 48,524 Saving in Cost (RM) 9327 11,207 11,607 12,005 12,377 B2: UTM Mosque

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Total energy (kW) 171,269 142,904 138,593 137,721 136,845 135,965 Total BEI 186 155 151 150 149 148 (kWh/yr/m2) Energy Saving (%) - 16.7 18.8 19.4 19.9 20.4

Cost (RM) 87,347 72,881 70,682 70,237 69,790 69,342

Saving in Cost (RM) - 14,466 16,665 17,110 17,557 18,005

Note: The exchange rate of Malaysia Ringgit to U.S. Dollars is 0.24 (as of 9 August 2021)

Subsequently, further simulations were carried 4. DISCUSSION out on both mosques to investigate the energy impacts of 1F operational profile and different The key results of this study are summarised in temperature setpoints. The selected temperature Table 8. The table shows that only two out of six setpoints were in the range of 24˚C and 27˚C studied mosques had a BEI below the baseline based on the thermal comfort temperature level of 135 kWh/m2/yr as suggested by Hussin et recommended in MS1525 (Department of al. (2019), namely A3 (Alam Damai Mosque) and Standards Malaysia, 2019) and findings by B1 (Kota Damansara Mosque). The remaining Hussin et al. (2019). The operation considered the four mosques with higher BEI than the baseline lighting profile, internal heat gains from level of 200 kWh/m2/yr as in MS1525 (2019) equipment, such as fans and computers, and the were A1 (Wangsa Melawati Mosque), A2 occupants (i.e., full occupancy was assumed (Bandar Baru Ampang Mosque), B2 (UTM based on the cooling area). As shown in Table 7, Mosque), and B3 (Hidayah Mosque) with a a reduction in energy consumption and cost could respective BEI of 230 kWh/m2/yr, 151 be seen when 1F operational profile was used. kWh/m2/yr, 191 kWh/m2/yr and 152 kWh/m2/yr. The range of energy and cost reductions for UTM These mixed results between mosques in group A Mosque were 18.8-20.4% and RM14,466.00- (with HVLS fans) and group B (without HVLS 18,005.00, respectively. For Wangsa Melawati fans) do not clearly show the superiority of one Mosque, the range of energy reduction was 14.8- group over the other in terms of energy 20.3%, while the range of energy cost reduction performance. This indicates that mosques was RM 9327.00-12,377.00. equipped with an HVLS fan may or may not consume more energy than mosques without any HVLS fan.

Table 8 : Summary of key results

BEI (kWh/m2/yr) Statistical Simulations (IESVE) MOSQUES analysis (SPSS) Adjusted Operational Setpoints Temp. (270C) of 2-year Setpoints profile (1F) and operational profile electricity bills Temp. (270C) (1F) MOSQUE WITH HVLS FAN A1: Wangsa Melawati Mosque 230 206 184 172 A2: Bandar Baru Ampang Mosque 151 A3: Alam Damai Mosque 111 MOSQUE WITHOUT HVLS FAN B1:Kota Damansara Mosque 133 B2: UTM Mosque 191 179 155 148 B3:Hidayah Mosque 152

The mosques ranked first (A3: Alam Damai maintaining the AC temperature setpoint at a Mosque) and last (A1: Wangsa Melawati minimum of 19˚C. The reason for this was that Mosque) in terms of energy consumption and the air conditioners in the main prayer hall were electricity cost were those with HVLS fan. This undersized; thus, a setting of 19˚C was done to result does not support the notion that using a help cooling down the hall faster. Research has ceiling fan in an air-conditioned area should help shown that AC temperature setpoints of 26˚C to reduce building energy consumption (Shah et al., 28˚C are more comfortable when a fan is 2015). The observation found that Wangsa provided than a temperature of 24˚C without a fan Melawati Mosque used the HVLS fan while (Zhai et al., 2019). Furthermore, the combination

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of air movement from the fan and the air since the average air temperature is as high as conditioners help to shorten the period to cool 31˚C. down the temperature. Indeed, using both HVLS fan and air conditioners can reduce the building However, it is also important to consider the energy consumption if the AC temperature duration of the AC operation. The current AC setpoint is increased to a certain degree. operation during weekly Friday prayer, which is performed at Zohor time from 12:00 pm to 3:00 The best profile of operating air-conditioners and pm, is acceptable as the air temperature is high, fans simultaneously to avoid energy wastage is and occupants stay longer in the mosque essential for building operators to consider. Wai compared to everyday Zohor prayer. During Asar et al. (2015) pointed out that understanding how prayer, which is generally performed between the cooling device work can reduce power 4:00 pm to 5:00 pm, it is essential to operate the consumption. Since mosques are unique in terms AC as the average temperature is around 28˚C. of function and operation, building operators During Maghrib and Isyak prayers, the operation need to understand the mosques' occupancy of the AC system may need to be reconsidered as profile to monitor and control the building energy the temperature during these hours is at 26˚C. usage, mainly when the occupancy level is high. During the daytime in the Ramadhan month, AC systems are typically run from 1:00 pm to 2:00 The study's simulation results indicate that a pm, which is acceptable considering the high air combination strategy of temperature setpoint and temperature. Furthermore, many activities (e.g. operational profile adjustments can produce itiqaf) are held during this time that attracts energy- and cost-savings. The study found that worshippers to spend a longer time at the mosque. both studied mosques could produce around 1- During Maghrib and Isyak times in the Ramadhan 4.9% energy reduction when the AC temperature month, the AC system is necessary as setpoint was increased by 1˚C and could result in worshippers tend to stay for long hours in the the highest cost-saving of about RM3,456.00 mosque to perform three prayers almost when the temperature was set at 27˚C. This consecutively (i.e. Maghrib, Isyak, and Taraweh). finding is in line with Armin and Sarip (2016), who proved that reducing AC temperature by 1˚C From the foregoing discussion, it appears that the could result in a 4-5% increment of building AC system operation is necessary during every energy consumption and the highest prayer time except for Subuh, during which the consumption, about 40% when the temperature air temperature is acceptable for thermal comfort. was set at 19.89˚C. Since the temperature setpoint Notably, however, the duration required for the directly impacts energy consumption, it is vital to AC to run during each prayer session needs to be look into occupants behaviour, particularly in further analysed to avoid energy wastage. The terms of AC temperature settings and duration of study revealed that mosques operated their AC usage (Yan et al., 2019a). Indeed, adjustments to systems every day for 30 minutes during Subuh higher AC temperature setpoints are effective for prayer, 1 hour each for Zohor and Asar; and a energy savings (Wang et al., 2013). continuous operation during Maghrib and Isyak. Furthermore, the mosques ran their AC systems Unlike office buildings with a fixed operational for 2.5 hours during weekly Friday prayers and 4 profile of 9:00 am to 5:00 pm, mosques' hours during Maghrib and Isyak prayers in the operational profile is based on prayer times. By month of Ramadhan. The study argues that these linking these prayer times with the local annual baseline operational profiles could be adjusted for air temperature, one can estimate the duration energy efficiency. required to run the AC. For example, data from the Malaysian Meteorological Department Therefore, a few simulations were performed on presented in Tang et al., (2017) highlighted that two mosques ranked lowest in energy the daily average, maximum, and minimum dry consumption and cost using a 19˚C temperature bulb temperature of Kuala Lumpur. A strategy for setpoint to investigate the impacts of using AC operation for each daily prayer time was different operational profiles (labelled as 1A to developed for energy efficiency guided by these 1F) building energy consumption. As shown in weather data. For instance, during Subuh prayer Table 7, operation profile 1F produced the highest time, which usually begins between 5:00 am to reduction in BEI for both mosques: 184 6:00 am (Malaysia time zone), the average air kWh/year/m2 for Wangsa Melawati Mosque (A1) temperature is 24˚C, as shown in Figure 3. This and 155 kWh/year/m2 for UTM Mosque (B2). temperature falls within an acceptable thermal The research evidence indicates that the most range; hence, it is sensible to suggest that AC's efficient daily AC operation profile is to use the operation is not required during this time. AC AC system for 30 minutes during Zohor, Asar, system operation may be necessary during Zohor Maghrib and Isyak, and leave the mosque prayer time, which is around 12:30 pm to 2:00 pm naturally ventilated during Subuh prayer. Instead

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of continuously operating the AC system from measures: Maghrib to Isyak, as currently practised, it would be more efficient to operate for 30 minutes during • AC temperature setpoints: AC system Maghrib, and 30 minutes during Isyak. The study consumes less energy when the temperature also demonstrates that it is more energy efficient setting is higher. Understanding the optimum to shorten the AC operation for 30 minutes during AC temperature setting when an HVLS fan is Friday prayers, i.e. to end at 14:30 hour instead of operated together is vital to avoid energy 15:00 hours. For the Ramadhan month, the study wastage without compromising the occupants' suggests that the AC operation time be 1 hour thermal comfort. It is worth considering the during Zohor time but reduced from 4 to 3 hours 10-minute cycle time for the AC system to during nighttime. cool down spaces before the prayer begins to have better indoor thermal comfort (Mustapa A 30-minute duration for AC operation is enough et al., 2017; Papadopoulos et al., 2019). to cool down mosque spaces. Previous studies • Building operation profile: Mosque have confirmed that it takes 15 minutes for the operates according to prayer time; hence, the AC system to operate before the prayer time to operation of mechanical ventilation should allow pre-cooling of the space, and the next 15 follow the prayer time. Dry bulb air minutes during the prayer time is adequate to temperature should be considered in the remove the indoor warm air (Stadler et al., 2009; operation setting (temperature and timing) of Wai et al., 2015; Welguisz et al., 1998). The 15- the mechanical ventilation system (Budaiwi minute duration is assumed as the air temperature & Abdou, 2013) supply factor where the constant air volume meets • Energy management knowledge of the cooling load in the occupied zone (Cheng et building operators: The government should al., 2018). Furthermore, the daily prayer time initiate educational programmes (e.g. lasts about 15 minutes from the start of Azan (Al- practical training or short seminars) for Homoud et al., 2005a). Once the prayer is mosque operators, especially those with no completed, the indoor air temperature can last for technical background, such as mosque another 10-15 minutes after the air-conditioner is officers. Such programmes would allow them turned off, assuming the AC system's ideal cycle. to enhance their knowledge of the proper handling of the mechanical ventilation system Still using the operation profile 1F as the baseline, to achieve energy efficiency. A standard further simulations were conducted on the studied operating procedure (SOP) or guideline mosques by incorporating the temperature would be useful for them (Hussin et al., 2014) setpoints within the thermal comfort range as • Equipment performance: Designer and recommended in the Malaysia Standard MS maintenance personnel should be trained 15252:2019, and Hussin et al. (2014). Table 7 better to understand the types of air presents the summary of the results with conditioners and fans to avoid installing temperature setpoints between 24˚C and 27˚C. undersized or oversized equipment, which These recommended four temperature setpoints would result in high energy consumption produced an energy savings range of 14.8% to (Shah et al., 2015). For HVLS fan, the size 20.4% and cost savings of between RM12,377.00 and motor efficiency should be considered. to RM18,005.00. These findings support earlier While the fan's air movement contributes to findings that suggest the temperature range of occupants' comfort, its usage does not reduce between 24˚C to 27˚C is acceptable for thermal the ambient temperature. The type of blade, comfort in hot and humid climates (Djamila et al., dimension and fan speed play an essential role 2013; Khalid et al., 2019). Although this study in air distribution (Othman et al., 2019; Zhai revealed that 27˚C of AC temperature setting et al., 2019). produced the highest reduction in BEI (average 20% energy saving and 20% cost saving), mosque 5. CONCLUSION operators can adjust the temperature setpoint according to the thermal preference of the This study has revealed the energy consumption worshippers. From the results of the Wangsa patterns of six studied air-conditioned mosques, Melawati Mosque and UTM Mosque simulations, with and without HVLS fan installed. Integration a temperature setpoint of 27˚C produced a BEI of of an HVLS fan in an air-conditioned mosque can 2 2 172 kWh/yr/m and 148 kWh/yr/m , respectively. reduce the building energy consumption without 2 These values are lower than 200 kWh/yr/m in compromising the occupants' thermal comfort if 2 MS1525:2019 and 181.9 kWh/yr/m in Al- both systems are operated optimally through Homoud et al. (2005b). proper temperature setpoints and operational profiles. This study has shown that increasing the Concerning the simultaneous usage of AC and AC temperature by 1˚C could result in 1-4.9% HVLS fans, the study recommends the following energy saving. A 30-minute AC operation during

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each daily prayer (except Subuh) could achieve part I : energy audit and use trends based 14.8-16.7% annual energy saving and about 15.2- on the analysis of utility billing data. 16.6% annual energy cost. This study has also Journal King Abdulaziz University : shown that a combined strategy of adjusting the Engineering and Science, 16(January), AC thermostat setting between 24-27˚C and 165–184. operating the AC for 30 minutes at every prayer https://doi.org/10.4197/Eng.16-1.10 time (but no AC operation during Subuh prayer) [3] Al-Homoud, M., Abdou, A., & Budaiwi, can produce up to 20% energy saving. In other I. (2005b). Mosque energy performance, words, the adjustment of temperature setpoints part II : monitoring of energy end use in alone will reduce minimal energy consumption. a hot-humid climate. JKAU: Eng. Sci., The combined strategies of appropriate 16(1), 185–202. temperature setpoints and building operational [4] Al-Homoud, M., Abdou, A., & Budaiwi, profiles are vital to maximising energy efficiency I. (2009). Assessment of monitored and minimising energy cost without energy use and thermal comfort compromising the occupant's thermal comfort. conditions in mosques in hot-humid climates. Energy & Buildings, 41, 607– 6. LIMITATION AND RECOMMENDATION 614. https://doi.org/10.1016/j.enbuild.2008.1 Since this study focuses on mosque buildings 2.005 with intermittent occupancy, the results may not [5] Al-shaalan, A. M., & Alohaly, A. H. A. apply to other building types with predictable (2017). Design strategies for a big occupancies, such as commercial buildings. mosque to reduce electricity Another limitation is that the study did not consumption in the Kingdom of Saudi consider the future weather profiles, as climate Arabia. The 21st World Multi- change will affect the air temperature. One Conference on Systemics, Cybernetics potential extension of this study is to obtain the and Information, Wmsci, 313–317. mosques' detail monitoring energy data, [6] Ali, H., & Hashlamun, R. (2019). including their indoor air temperatures, to Envelope retrofitting strategies for optimise the mosques' setpoint temperatures. The public school buildings in Jordan. study recommends these outcomes be considered Journal of Building Engineering, in the energy management guidelines for mosque 25(May), 100819. buildings in Kuala Lumpur. Relevant educational https://doi.org/10.1016/j.jobe.2019.100 programmes for mosque operators, especially 819 those without any technical background, are vital [7] Ariosto, T., Memari, A. M., & Solnosky, to lowering mosques' energy consumption while R. L. (2019). Development of designer maintaining indoor thermal comfort. aids for energy efficient residential window retrofit solutions. Sustainable Energy Technologies and Assessments, 7. ACKNOLEDGEMENTS 33(February), 1–13. https://doi.org/10.1016/j.seta.2019.02.0 A special thanks to Ustaz Azahari from the 07 Wangsa Melawati mosque and the Department of [8] Ascione, F., Bianco, N., De Masi, R. F., Asset & Development staff, Universiti Teknologi Mastellone, M., Mauro, G. M., & Malaysia (UTM) Kuala Lumpur, for giving Vanoli, G. P. (2020). The role of the permission to conduct this research at the selected occupant behavior in affecting the mosques. feasibility of energy refurbishment of residential buildings: Typical effective 8. REFERENCES retrofits compromised by typical wrong habits. Energy and Buildings, 223(2020), 110217. [1] Aghniaey, S., & Lawrence, T. M. https://doi.org/10.1016/j.enbuild.2020.1 (2018). The impact of increased cooling 10217 setpoint temperature during demand [9] Atmaca, A. B., & Gedik, G. Z. (2019). response events on occupant thermal Evaluation of mosques in terms of comfort in commercial buildings : A thermal comfort and energy review. Energy & Buildings, 173, 19– consumption in a temperate-humid 27. climate. Energy & Buildings, 195, 195– https://doi.org/10.1016/j.enbuild.2018.0 204. 4.068 https://doi.org/10.1016/j.enbuild.2019.0 [2] Al-Homoud, M.,Abdou, A., & Budaiwi, 4.044 I. (2005a). Mosque energy performance, [10] Barthelmes, V. M., Becchio, C., Fabi,

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